One of the most common and least expensive ways of getting audio from your iPod into your vehicle is with the use of an FM Transmitter. An FM Transmitter usually connects to the headphone output of your iPod (or other audio device), and converts the signal into a radio frequency transmission that can be tuned on any FM radio. FM Transmitters are not just for cars as they also work with home stereo systems, boom boxes, or any FM band radio.